Settling tank



SETTLING TANK Filed May 2l, 1934 2 Sheets-Sheet 2 SWW/wie@ Patented Aug.18, 1936 SETTLING TANK Carl II. Nordell, Chicago, Ill., assigner toLakeside Engineering Corporation, Chicago, Ill.

Application May 21, 1934, Serial No. 726,684

4 Claims.

'I'his invention relates to a settling tank, more particularly designedfor settling sewage although of course not limited to this particularuse. In the conventional type of settling tank, the sewage 5 owsdirectly across the tank. 'I'he current thereby created and the currentscreated by the movement of the sludge collectors set up countercurrentscausing persistent whirls. These whirls collect and form more or lesspermanent clouds of sludge which greatly 'interfere with the settlingand the general eiliciency of the tank.

The principal object of the present invention is to provide a settlingtank which will have a harmonious and coordinated ow so as to eliminatethese whirls, and their resultant clouds so as to constantly maintain ahigh eiilciency in the tank.

Another object of the invention is to so construct the tank that itssettling coeiiiciency will be independent ofthe amount of, or thevariations in, the incoming solution.

A further object is to so construct the mechanical portions of thedevice that they will be long wearingwill require but a minimum ofattention and but a minimum of power. Other objects and advantagesreside in the detail construction of the invention, which is designedfor simplicity. economy, and eiiiciency. These Iwill become moreapparent from the following description.

In the following detailed description of the invention reference is hadto the accompanying drawings which form a part hereof. Like numeralsrefer to like parts in all views of the drawings and throughout thedescription.

i In the drawingsz- Fig. 1 is a vertical cross section through a tank inwhich the invention is embodied.

Fig. 2 is a plan view thereof, partly in section. Fig. 3 is a detailsection of the central shaft 40 thereof.

The invention comprises a settling basin .or tank I0, preferablyformedof concrete with a hexagonal shape. The walls of the tank III aresurmounted by a beam section I2 which projects both inwardly andoutwardly beyond the wall faces so as to increase the thickness thereofat the top. 'Ihe tank is provided with a conical bottom I3 inclining toa sludge pocket I4 at the 50 center thereof. Av sludge draw-off pipe I5leads from the pocket I4. The beam section I2 increases the strength ofthe tank. provides a walkway about the tank, and provides means forvsuspending a cylindrical baille II within the tank. The baille IIextends entirely around the tank I terminating a short distance abovethe bottom I3.

The solution to be settled is fed into the tank I0 through an influentchannel I6 which preferably enters the tank tangentially of the bafile 5wall II. However if this is not convenient, it may be led directlythrough the wall, as illustrated, and discharged through a tangentiallyarranged bale hood I1 which will direct the flow tangentially of thebaiile wall Il.

It will be noted that the overhang of the beam section I2 provides aperipheral space between the baille wall Il and the tank walls entirelyaround the bale which will be herein designated as the race I8. Thisrace constantly changes its width, owing to the relative di'erencesbetween the circular baiiie and the hexagonal tank.

A structural superstructure I9 extends across the top of the tank I0 andsupports an annular. Weir ring therein substantially at the solu- 20tion level. The Weir ring is suspended by means of suitable hangers 2|from the super-structure and communicates with an eiiluent trough 22which leads through the baille II'and the Wall of the tank I0 to aneiiluent channel 23. The 25 and is supported therein on a thrust bearing28 at -35- the top. A steady bearing 29 of rubber, wood or downwardlyalong the botto'm I3 to the sludge other suitable material is placed atthe bottom of the shaft housing to absorb lateral strains on theshaft2'l.

'I'he shaft 21 terminates at its bottom in a T- fitting 30 from whichextend two oppositely positioned, inclined, scraper arms 3| which aresupported and braced from the shaft 21 by means of suitable tie-rods 32.A series of flat, sheet metal plows 33 are secured in spaced relationthroughout the length of the scraper arms 3l by means of suitable clamps34. 'I'he Scrapers or plows are set at an angle which will carrymaterial pocket I4. The outer extremities of the scraper arms 3| arepreferably supported upon wheels 35 so that they will maintain a uniformdistance from the bottom I3.y The axial portion of the arms may beadjusted up or down to maintain this distance uniform by means of asuitable spacer 36 beneath the thrust bearing 28.

The shaft 21 is rotated from a suitable motor The influent is controlledby means of a suitable 15 stop gate 42 so that it will havesubstantially the same velocity as the vortex current caused by therotating scraper arms 3l which rotate in 'the same tangential direction.

downward spiral movement is imparted to the 20 iniluent in the race III,and,'as the mixture of sludge and sewage strikes the corners of thetank, there is a gentle mixing action which greatly aids infiocculation.Thesewage ilows beneath the baiile I I in a tangential directionandrises ,25 to the weir rin'g 20 in a gentle contracting spiral.

'I'here are two distinct hydraulic motions in the settling compartment,the very slow upward flow to the weir ring 2li, and the faster rotarynow produced by the method of introducing the sewage 30 and the actionof the .rotating scraper arms. These movements are at right angles toeach other and do not interfere to cause counter currents or"clouds" ofsludge as in the usual machine. 'I'he rotary iiow has the same direction435 and substantially the same velocity as the scraper arms 3|, hencethe motion of the sludge scraper arms, and eilluent, are so synchronizedthat turbulence and the formation of clouds is avoided and a highsettling eillciency-is obtained.

40 since the thrusted bearing za is rar above the solution line, it canbe emciently lubricated. The

steady bearing 29 needs no lubrication other tl'ianv that obtained fromthe sewage itself.

While the tank I is illustrated as hexagonal,

sired to be understood that the same may be l varied, within the scopeof the appended claims, without departing from the spirit of the inven-55 tion. f

Having thus described the invention, what is Therefore should an Thus aslow which is probably the preferable shape, `it need4 gained anddesired securedQ by Letters Patent v1.y A settling device comprising: ahexagonal tank; a conical bottom in said tank: means for removingmaterial from the lowest point of said 5 bottom; a cylindrical baillemember.v extending into said tank in spaced relation with the walls andbottom thereof; an annular, channel-like, weir ring lsuspendedsubstantially at the solution line within said baille member; means forconl0 ducting solution from said ring through the wall of said tank; andmeans for supplying solution to the space between said walls and saidbaille 'memben said'latter means being arrangedl to deliver saidincoming solution tange'ntially of said l5 baille member. 2. A settlingdevice comprising: a hexagonal tank; a conical -bottom in said tank;means for removing material from the lowest point of said bottom; acylindrical baille member extending into said tank in spaced relationwith the walls and bottom thereof; an annular, channel-like weir ringsuspended substantially at the solution line within said baille member;means for conducting solution from said ring through the wall of saidtank; means for supplying solution to the space between said walls andsaid banle member; a superstructure'extending over said tank; avertical, shaft lhousing suspended from said structure within seid tank;a vertical shaft within said housing terminating adjacent thebottom ofsaid tank; and scraper arms extending from said t and provided withrakes to rake material tow the low point of said bottom.

3. A settling device comprising: a hexagonal tank; a conical bottom insaid tank; means forv removing material from the lowest point of saidbottom; a cylindrical baille member extending into said tank in spacedrelation with the walls and bottomV thereof; an annular, channel-like,weir ring suspended substantially at the solution line within saidbaiile member; means for conducting solution from said ring through thewall of said tank; and means for supplying solution to the space betweensaid wallsand said baille member; an inwardly projecting beamv along thetop of the walls of said tank, said beam acting as' a spacer and asupport for said baille member.

4. In a settling tank: means for receiving the' 'overflow of said tankcomprising: an annular channel member suspended substantially at thesolution line of said tank; a seriesof weirs formed u in the walls ofsaid channel member; and a conduit for receiving the contents ofsaidchannel member.

` CARL H. NORDELL.

